#include<windows.h>

// winmm.lib をリンクする
#pragma comment(lib,"winmm")

#define SRATE	8000	//標本化周波数(1秒間のサンプル数)
#define F		400		//周波数(1秒間の波形数)

LRESULT CALLBACK WindowProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
	WAVEFORMATEX wfe;
	static HWAVEOUT hWaveOut;
	static WAVEHDR whdr[2];
	static LPBYTE lpWave[2];
	int i,len,k;

	static int buf_num;
	HDC hdc;
	PAINTSTRUCT ps;
	char str[32];

	switch(uMsg){
		case WM_CREATE:
			wfe.wFormatTag=WAVE_FORMAT_PCM;
			wfe.nChannels=1;	//モノラル
			wfe.wBitsPerSample=8;	//量子化ビット数
			wfe.nBlockAlign=wfe.nChannels * wfe.wBitsPerSample/8;
			wfe.nSamplesPerSec=SRATE;	//標本化周波数
			wfe.nAvgBytesPerSec=wfe.nSamplesPerSec * wfe.nBlockAlign;

			waveOutOpen(&hWaveOut,WAVE_MAPPER,&wfe,(DWORD)hWnd,0,CALLBACK_WINDOW);

			len=SRATE/F;	//波長
			for(k=0;k<2;k++){
				lpWave[k]=(LPBYTE)calloc(wfe.nAvgBytesPerSec,2);	//2秒分

				for(i=0;i<SRATE*2;i++){	//波形データ作成
					if(i%len < len/2)	lpWave[k][i]=128+64;
					else				lpWave[k][i]=128-64;
				}

				whdr[k].lpData=(LPSTR)lpWave[k];
				whdr[k].dwBufferLength=wfe.nAvgBytesPerSec * 2;
				whdr[k].dwFlags=WHDR_BEGINLOOP | WHDR_ENDLOOP;
				whdr[k].dwLoops=1;

				waveOutPrepareHeader(hWaveOut,&whdr[k],sizeof(WAVEHDR));
			}
			return 0;
		case WM_LBUTTONDOWN:
			for(k=0;k<2;k++){
                waveOutWrite(hWaveOut,&whdr[k],sizeof(WAVEHDR));
				whdr[k].dwUser=0;
			}
			return 0;
		case WM_RBUTTONDOWN:
			waveOutReset(hWaveOut);
			for(k=0;k<2;k++){
				whdr[k].dwUser=1;	//waveOutReset関数を呼び出した
			}
			return 0;
		case MM_WOM_DONE:
			if(((LPWAVEHDR)lParam)->dwUser){	//waveOutReset関数で停止した
				buf_num=0;		//初期値に戻す
			}else{		//最後まで再生した
				waveOutWrite((HWAVEOUT)wParam,(LPWAVEHDR)lParam,sizeof(WAVEHDR));
				for(k=0;k<2;k++){
					if((LPWAVEHDR)lParam==&whdr[k]){
						buf_num=k;		//再生を終了したバッファ
						break;
					}
				}
				buf_num=(buf_num+1)%2;		//再生中のバッファ
			}
			InvalidateRect(hWnd,NULL,TRUE);
			return 0;
		case WM_PAINT:
			hdc=BeginPaint(hWnd,&ps);
			wsprintf(str,"再生中のバッファ = %d",buf_num);
			TextOut(hdc,0,0,str,lstrlen(str));
			EndPaint(hWnd,&ps);
			return 0;
		case WM_DESTROY:
			waveOutReset(hWaveOut);
			for(k=0;k<2;k++){
                waveOutUnprepareHeader(hWaveOut,&whdr[k],sizeof(WAVEHDR));
			}
			waveOutClose(hWaveOut);
			for(k=0;k<2;k++){
                free(lpWave[k]);
			}
			PostQuitMessage(0);
			return 0;
	}
	return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain(
	HINSTANCE hInstance,HINSTANCE hPrevInstance,PSTR lpCmdLine,int nCmdShow)
{
	WNDCLASS wc;
	MSG msg;

	wc.style		 = CS_HREDRAW | CS_VREDRAW;
	wc.lpfnWndProc	 = WindowProc;
	wc.cbClsExtra	 = 0;
	wc.cbWndExtra	 = 0;
	wc.hInstance	 = hInstance;
	wc.hIcon		 = LoadIcon(NULL,IDI_APPLICATION);
	wc.hCursor		 = LoadCursor(NULL,IDC_ARROW);
	wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
	wc.lpszMenuName	 = NULL;
	wc.lpszClassName = __FILE__;
	if(!RegisterClass(&wc)) return 0;

	HWND hWnd=CreateWindow(
		__FILE__,"WAVEのマルチバッファリング",
		WS_OVERLAPPEDWINDOW | WS_VISIBLE,
		CW_USEDEFAULT,CW_USEDEFAULT,
		CW_USEDEFAULT,CW_USEDEFAULT, 
		NULL,NULL,hInstance,NULL);
	if(hWnd==NULL) return 0;

	BOOL bRet;
	while((bRet=GetMessage(&msg,NULL,0,0))!=0){
		if(bRet==-1) break;
		DispatchMessage(&msg);
	}

	return (int)msg.wParam;
}